This invention generally relates to internal combustion engines, and more particularly to internal combustion engines especially well-suited for high fuel compression ratios.
Internal combustion engines are typically comprised of one or more cylinders each having a piston which reciprocates therein. The reciprocating motion of the piston is converted to rotary motion of a crankshaft by virtue of a connecting rod, which has a first end pivotally connected to the piston and a second end pivotally connected to an eccentric portion of the crankshaft. In operation, an explosive mixture, illustratively comprised of gasoline or oil vapors mixed with air in a predetermined ratio, is conducted into an engine cylinder, a piston is reciprocated to compress the explosive mixture in the engine cylinder, and power is obtained from this engine by igniting this mixture when the piston has fully compressed it.
Prior art engines of the general type described above have received wide commercial acceptance and are extensively used in a great variety of circumstances. Nevertheless, it is believed that these engines may be improved in several respects. To elaborate, with the above-described arrangement, forces are transmitted from the crankshaft to the piston to compress the explosive vapors in the cylinder chamber; and immediately following the ignition of these vapors, forces are transmitted from the piston to the crankshaft to rotate the crankshaft. These forces tend to have opposite affects on the crankshaft, resulting in what may be considerable internal stresses in the crankshaft. These stressses may be substantially exacerbated in multi-cylinder engines, where opposing forces may be simultaneously applied to adjacent portions of the crankshaft.
In multi-cylinder high compression ratio engines--that is, in engines where the explosive vapor in the cylinder chambers is compressed to a pressure of about 10 or 12 times its normal pressure--the internal stresses in the crankshaft are quite severe; and often, in order to withstand these stresses, the crankshafts of such engines must be constructed of special, high-strength alloys. Because these alloys are specifically developed for this use, they tend to be fairly expensive. Consequently, the use of high compression engines has been avoided in many applications where engine costs are of paramount concern.
In addition, in internal combustion engines of the general type outlined above, the rods connecting the pistons with the crankshaft often swing from side to side over a relatively large arc as the engine pistons reciprocate within the engine cylinders. This swinging movement of the connecting rods urges the pistons laterally against the engine cylinder walls. This, in turn, increases the friction within the engine, reducing its efficiency and its effective work life. Furthermore, with a typical prior art internal combustion engine, it is very difficult to adjust or to vary the compression ratio of the engine. Often, this can be done only by disassembling a major portion of the engine and replacing various parts thereof. This is very time consuming and expensive and, of course, cannot be done while the engine is operating.
Various prior art internal combustion engines have been designed to alleviate one or more of the above-discussed, or other, disadvantages, especially the lateral swinging movement of the connecting rod. Many of these engines employ two rods to connect the piston to the crankshaft, with a lever connecting together these two connecting rods. Such engines, for example, are disclosed in U.S. Pat. Nos. 242,401; 939,669; 1,625,835; 1,978,058; 2,390,558; 2,493,718; and 2,659,351. It is believed that the engines disclosed in these references do not satisfactorily resolve all the difficulties outlined above, and in particular do not effectively reduce the internal stresses on the crankshafts of the engines.